Sound-transmitting diaphragm, composition therefor, and method of making the same



G. S. KNOX'. some!) TRANSMHTUJG mAPuflAemycomPosmow 'i-(EREFO R, AND METHOD OF MAKING THE SAME. 6,2921

APPLICATION FILED HM Patented Apr. 11, 1922.

To all whom concern:

ra'rrzu'r ornce.

.-um1'eo srargs 1 cnomn s knox, 01 ms'r ORANGE, mew .rnnsnr.

soummmsltmme msrnasc com'osmon THEREFOR, AND METHOD or t mine rnnsmn Specification of Letters Patent.

Patented Apr. 11 1922.

Application filed m a, 1921. Serial No. 467,500.

Be it known that I, Gnoacn S. Knox, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Sound Transmitting Diaphragms, Compos1t1on Therefor, and Methods 0. Making the Same; and I do hereby declare the following to be a full, clear, and exact description of the 1nvention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to characters of 15". reference marked thereon, which form a part of this specification.

This invention relates to improvemen'tsin sound transmitting diaphragms; and the 1nvention has reference to a novel composition of materials for, and a novel method of, making such sound transmitting diaphragms, as well as to the diaphragm per so as a finished product or article of manufacture.

The invention has for its principal object to provide a very durable, flexible and sensitive sound transmitting diaphragm for phonographic, telephonic and similar uses, which is comprised of a plurality of materials producing a novel composition for the purposes mentioned, and which is made in a novel manner, all to the end that in opera tion the diaphragm is long lived and capable ductionof the complete diaphragm.

Fi urefz is a plan or face view of a finished diap iragm', and Figure'3 is a cross section through the-same, the thickness thereof being somewhat exaggerated.

Figure 4 1s a vertical cross se ctionfof a phonograph reproducer, showing my novel diaphragm assembled operatively therewith, the latter being shown in elevation.

Figure 5 is a face view of my novel diaphragm as arranged for telephonic use; and Figure 6'is an edge view of'the same.

Similar characters of reference are employed in all of the above described views, to 0 indicate corresponding parts.

The composition of ingredients from which the novel diaphragm material is produced, consists of alcohol, ether, gun-cotton,

castor oil, resin, shellac and a coloring mat- 5 vter, such, e.'g., as lamp-black.

While the relative proportions in which said ingredients may be used is subject to more or less variation, I have found the following proportions very effective in producing-a diaphragm for phonographic uses,

to wit I Alcohol 36 parts by weight. Ether 36 parts by weight. Gun-cotton 5 parts by weight. Castor oil 1 part by weight. Resin "12 parts by weight. Shellac 10 parts by weight.

' When used in the above stated proportions, there may be added to the mass a quantity of coloring matter, such as lampblack, equivalent to one per cent of the total mass. i id The manner of combining or'mixing the ingredients above named to produce the initial composition is as follows The major portion ofthe alcohol and the ether' are first mixed together, whereupon the cotton is stirred therein and dissolved. The castor oil is then added to the mixture to form the preliminary solution. A small portion of the alcohol (which has been retained for the purpose) is then used to dissolve the shellac and. resin, to thus produce.

a fluid mixture of the latter ingredients.

The fluid mixture of shellac and resin is then added to the cotton-caster oil preliminary solution, and the whole mass thoroughly agitated and mixed together. Finally, the

damp-black or other desired coloring matter is added and- -tliorough1yintermixed with consequently the final solution to complete, the composition 1. U

The composition 1 having been thus prepared, and while in fluid state, is apphedto a fabric material 2. This fabric material, which is preferably linen, is stretched to hold the same taut, w iereupon the composition is applied. by washing, brushing or otherwise to both sides of the fabric to thoroughly impregnate the latter therewith and to evenly coat its opposite faces.

After the fabric 2 has been thus treated With the com osition 1 it is allowed to dry, after which t e resultant material is submitted to heat and pressure for the purpose of compressing, curing and hardening the same. lipon the completion of the curing and hardening steps, the material is trimmed to produce the final size and shape of diaphragm desired, resulting in" he finished diaphragm I) (see Figure The composition l, reentorced by the inobeddedfabric 2, provides a novel and highly cllicient diaphragm for sound transmitting and similar purposes; the being sufficiently flexible and sensitive to readily rcspond to the vibrations transmitted thereto, whereby, when vibrated, it causes very accurate reproduction of sounds and musical tones, reproducing the same with exceptional clcarness and smooth rich quality without harshness or metallic timbre.

The novel diaphragm, constructed as .above described, will readily withstand all ordinary strains in use, and the same will not crack, flake, peel or fracture, neither will the same buckle or warp out of shape; the composition embodied in the novel structure aflords an ideal material for phonograph reproducer diaphragms. When used for such a purpose, the same is clamped at its margins to the main body 3 of the reproducer by means of the clamp ring 4 in the usual manner. (See Figure 4.) The upper end of the pivoted vibrator arm 5 of the reproducer is rigidly connected to the center of the diaphragm by any suitable means, so that the oscillations of the arm 5,

produced by the travel. of the needle 6 (fixed to its lower end) over a phonograph rep-0rd, are transmitted to the diaphragm to thereby vibrate the same and cause the reproduction of the sounds or mtlsical tones in the usual manner.

Referring now to Figures drawings, I have shown my novel diaphragm as arranged for telephonic use. As thus arranged I fix to its central portion a metallic button or disc 7 which ves as an armature, whereby the'diaphragm is caused to respond 5 and (i "of the im ulses.

, Iaving thus described my invention, I claim l. A composition for making sound transmitting (.liaphragms and the like, comprising a mixture of alcohol, ether, gun-cotton, castor oil, resin and shellac.

2. composition for makin sound transmitting diaphragms and the like, comprising by Weight 36 parts of alcohol, 2-56 parts of ether, 5 parts of gun-cotton, 1 part of Castor oil, 12 parts of resin and 10 parts of shellac, adapted to be mixed together, spread upon a fabric base while in liquid state, dried and then hardened and cured by heat and pressure.

3. A sound transmitting diaphragm comprising a fabric imbedded in a compound of alcohol, ether,gun-cotton,caster oil, resin and shellac to form a thin compositesheet, said compound being dried and then hardened and cured by the.application of heat and pressure to said. sheet.

i. The process of makingdiaphragm material comprising/first preparing a liquid solution of alcohol ether, gun-cotton, castor oil, resin and shellac; then-coating a fabric material with said solution to imbed said fabric therein; then drying the coated fabric; and finallylsubmitting the dried or vibrate under the influence of. magnetic coated fabric to heat and pressure for the purpose of hardening and curing the same.

5. The process of making diaphragm material comprising first preparing a solution containing bywveight 36 parts of alcohol, 36 parts of ether, 5 parts of gun-cotton, 1 part of castoai oil, 12 parts of resin and 10 parts of'shellac; then coating a thin fabric material, such as linen, with said solution to impregnate said fabric therewith and imbed the same therein; then drying the fabric thus treated with said solution; and finally submitting the dried treated fabric to heat and pressure for the purpose of hardening and curing the compound provided by said solution.

6. A diaphragm structure consisting of a compound of alcohol, ether, gun-cotlxm, castor oil, resin and shellac, vformed into a thin sheet, dried and then hardened'by heat and pressure, and a layer of thin fabric material imbedded in said sheet thus provided.

In testimony that I claim the invention set forth above I have hereunto set my hand this th day of April, 1921.

, GEORGE S. KNOX.

\Vitnesses Gnoncn D. Rrona'nns, Fnnnn. C. Fimnnrzn'n. 

